As wireless technologies proliferate, mobile wireless devices incorporate a multiplicity of different wireless standards. For example, a cellular telephone can accommodate a cellular network (e.g., Universal Mobile Telecommunications System), a wireless local area network (“WLAN”), such as IEEE 802.11, and a wireless personal area network (“WPAN”) (e.g., BLUETOOTH). Including WPAN access makes utilization of a wireless device more convenient by allowing use of wireless headsets and other short-range wireless appliances. Such phones are sometimes referred to as “smart phones.”
Mobile wireless devices are sometimes capable of accessing multiple exclusive wireless networks. Such wireless networks can occupy adjacent or overlapping parts of the frequency spectrum. For example, both BLUETOOTH and IEEE 802.11b/g/n utilize the 2.4-2.5 GHz band. Access to the networks can be coordinated via time multiplexing or frequency multiplexing to reduce performance degradation caused by collisions that may occur when the networks are simultaneously accessed. However, such multiplexing is often at the cost of shorter medium time available to each radio and thus lower performance, as a radio may be blocked from transmitting or receiving packets temporally to avoid collisions.
One technique to coordinate the use of the wireless medium between different wireless protocols that may interfere with each other is through the use of a frame such as the CTS-2-Self (C2S) frame (CTS stands for Clear To Send). A C2S frame commands all other wireless stations on a wireless local area network (WLAN) that receive the C2S frame to avoid transmitting on the wireless network for a period of time indicated in the C2S frame itself. A C2S frame thus places a WLAN in a non-communication mode. Repeated transmissions of C2S frames therefore reduce the performance of a WLAN.